As a preparative separation technique, electrophoresis offers the substantial advantage of the ability to separate species which are otherwise very difficult to separate, notably macromolecules and biochemical species in particular. Preparative separations involve the consolidation of solute zones emerging from the column and the transport of these zones to a fraction collector arrangement without permitting them to recombine.
The need to remove the eluting solute zones without disturbing the separation gel or the electrical potential imposed across it has led to some rather complicated and awkward apparatus constructions. Difficulties encountered with these constructions include irregularities in the fluid flow such as dead volumes and eddies which disturb the zones during transport, inadequate support of the separation gel, and complicated procedures for assembly and disassembly.
The present invention overcomes these difficulties by providing apparatus in the form of a collar and associated parts for securement to one open end of a tubular electrophoresis column (hereinafter "the Column"), and designed such that once secured in this manner, it can be immersed in a buffer solution (i.e., the lower buffer solution for a vertical column) to draw small amounts of the buffer solution across the bottom of the Column toward a centrally located point, from which these small amounts of buffer solution, containing eluting solutes, are removed to a fraction collector.
The collar is adapted to secure a porous plate and a dialysis membrane to the open end of the Column, the porous plate defining a space to receive the eluting solutes, and the dialysis membrane isolating the eluting solutes from the lower buffer solution while permitting electrical contact between the gel and the lower buffer solution. The lower buffer solution is drawn into the region of the porous plate through channels in the inside wall of the collar, and the withdrawal port is arranged to draw lower buffer solution from the periphery of the porous plate to a central point, thereby consolidating and collecting each individual solute zone prior to withdrawing it from the gel region,
Among the various preferred embodiments are those in which the collar is adapted to attach to the Column by a clamp and the channels are furrows along the interior wall of the collar, aligned parallel to the collar axis and regularly spaced. The invention extends to systems where the consolidated solutes are drawn down from the Column, in the same direction as the movement of the zones through the Column, as well as those in which the consolidated zones are drawn upward or back through the Column along the Column axis.
Further advantages, embodiments and objects of the invention will be apparent from the following description.